🐛 Fix Invalid Geometry in JSON Outputs

[shaneahmed]

• Replace direct Polygon construction with validated geometry via feature2geometry and make_valid_poly.
• Ensure all shapes are repaired and valid before JSON export.
• Prevents malformed or invalid polygons from breaking QuPath JSON outputs.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.88%. Comparing base (36ecfa6) to head (f6107f7).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1057      +/-   ##
===========================================
- Coverage    99.88%   99.88%   -0.01%     
===========================================
  Files           85       85              
  Lines        11576    11572       -4     
  Branches      1513     1513              
===========================================
- Hits         11563    11559       -4     
  Misses           6        6              
  Partials         7        7              

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[shaneahmed]

I have checked the outputs on QuPath. The bug is fixed now.

[Jiaqi-Lv]

I have tried it and it works.